To increase the gain of a single package, the package should have stages of transistors therein connected in series. As a technique for such transistor stages to be formed on a single semiconductor substrate together with associated matching circuits and bias circuits, the MMIC (Monolithic Microwave Integrated Circuit) has been actively used.
To implement the MMIC, there has been use of a semiconductor substrate with circuitry integrated thereon including semiconductor devices, input and output matching circuits, capacitors, power supply lines, and so on, as necessary.
Such the MMIC had a combination of transistors and matching circuits formed on a single substrate, with a fixed dielectric permittivity. As a result, for provision of greater capacitors or longer lines, the circuit configuration needed an increased area.
For the MMIC, there are applicable transistors including, among others, SiC (silicon carbide) transistors and GaN (gallium nitride) transistors having higher output power than transistors having been used ever, including, among others, Si (silicon) transistors and GaAs (Gallium Arsenide) transistors. However, applicable materials such as SiC and GaN are more expensive than materials used such as Si and GaAs, and cost high the MMIC to be provided with circuitry of anyone of those, including semiconductor devices, matching circuits, and bias circuits formed on a substrate.